The Habitability Habit: Exaggerating Earth-Likeness
Secularists put too much hope on some aspects of Earth-like exoplanets, but sometimes reality keeps their imaginations in check.
Titanic blunder: One of the most extreme cases of astrobiological folly in recent memory is the public presentation of Titan as a more habitable place for humans than Mars. Space.com and Fox News Science, fully aware that it’s -290°F at the surface of this large moon of Saturn, joined in this imagination fest, lured by the thought of free energy. Cassini scientist Amanda Hendrix and co-author Yuk Yang look at all the free oil and wind power down there, as if that’s all that matters. No food, no oxygen, and a billion miles of space travel are minor matters to these speculators who will never have to be held accountable for their ideas, since they will be long gone by the time humans leap the technological hurdles to even get there, let alone be able to land without freezing solid instantly. Besides those challenges, future settlers had better not bring or manufacture oxygen, otherwise with all the hydrocarbons present in the atmosphere, the settlement will go kablooey first time someone lights a match.
Artwork for one of Cassini’s 127 Titan encounters
Blunders like this come from focusing on one aspect of habitability to the exclusion of others. Titan orbits within Saturn’s magnetosphere 95% of the time, where it is exposed to high-energy charged particles. Lacking a magnetic field of its own, it is exposed to the deadly solar wind the other 5% of the time. Furthermore, Titan’s atmosphere is poisoned with acetylene, benzene and other toxins. It has smog, obscuring any view of the stars from the surface. And it is so deadly cold, any life form not continuously heated would die instantly. The ice on Titan is so cold, in fact, it behaves like solid rock. The only places for boat recreation are lakes of liquid methane and ethane. Titan does not seem like a fun place for humans to go, even with all that free oil. The occasional speculations about microbes on Titan seem highly unrealistic. If evolutionists cannot figure out how microbes came into being on an ideal planet like Earth, how can they imagine it happening on a world where all the water is locked up in ice?
TRAPPIST Entrapment: A few weeks ago, the news media hyped the TRAPPIST-1 star as a place to look for life. Its seven planets, three within the ‘habitable zone’ where liquid water might exist, excited the imaginations of astrobiologists leaking their hopeful dreams to the press. Now, there’s bad news. Mike Wall reports on Space.com, “The potentially Earth-like planets in the TRAPPIST-1 system may not be so conducive to life after all, two new studies report.” The onslaught of flares and outbursts from the parent star likely destroyed the atmospheres of all these planets, if they have or had them. Harvard astronomer Avi Loeb says with humorous understatement, “This would hurt the chances of life forming or persisting.” The blessings we enjoy on Earth stand out in this excerpt:
But it gets worse. Because the TRAPPIST-1 system is so tightly packed, the star’s magnetic field has likely connected with those of the planets, allowing stellar-wind particles to flow directly onto the worlds’ atmospheres, the researchers found. This has probably caused atmospheric degradation, and the worlds may even have lost their air entirely.
“The Earth’s magnetic field acts like a shield against the potentially damaging effects of the solar wind,” study leader Cecilia Garraffo of the CfA said in the same statement. “If Earth were much closer to the sun and subjected to the onslaught of particles like the TRAPPIST-1 star delivers, our planetary shield would fail pretty quickly.”
The type of star matters to habitability, Phys.org emphasizes. Having studied the destructive power of red dwarf stars, known for their flaring behavior, one co-author cautioned, “our work and the work of our colleagues shows we should also target as many stars as possible that are more like the Sun.”
The shooting gallery: A paper in PLoS One examines the biological effects of exposure to space outside the Earth’s protective shield. It begins, “During interplanetary flights in the near future, a human organism will be exposed to prolonged periods of a hypomagnetic field that is 10,000 times weaker than that of Earth’s.” The authors are primarily interested in the source of the magnetic sense in humans and animals, but they acknowledge that “Nonspecific magnetoreception could be of fundamental importance in terms of health risks caused by a chronic EM exposure of humans and biosphere.”
This would hurt the chances of life forming or persisting.
No fans for popular stars: Another article on Phys.org indicates that “cool stars favoured by exoplanet hunters” are unlikely to be habitable, even though more abundant than solar-type stars. Because an exoplanet’s habitable zone would be closer into a cool star, it would be exposed to coronal mass ejections (CMEs) at closer range. NASA Goddard scientists evaluated one such star (V374 Pegasi) and thought about conditions on a planet in the habitable zone, even if the planet had a magnetic shield:
When a CME impacts a planet, it compresses the planet’s magnetosphere, a protective magnetic bubble shielding the planet. Extreme CMEs can exert enough pressure to shrink a magnetosphere so much that it exposes a planet’s atmosphere, which can then be swept away from the planet. This could in turn leave the planetary surface and any potential developing lifeforms exposed to harmful X-rays from the nearby host star….
“While these cool stars may be the most abundant, and seem to offer the best prospects for finding life elsewhere, we find that they can be a lot more dangerous to live around due to their CMEs” said Marc Kornbleuth, a graduate student involved in the project.
The results suggest that an exoplanet would need a magnetic field ten to several thousand times that of Earth’s to shield their atmosphere from the cool star’s CMEs. As many as five impacts a day could occur for planets near the ACS [Astrospherical Current Sheet], but the rate decreases to one every other day for planets with an inclined orbit.
Law of mass action: What if Earth were 50% bigger? Live Science says it would preclude our space program. It already takes 80-90% of the mass of a rocket just for propellant to launch humans into space. At some point, as the mass of a planet grows, it reaches a point of diminishing returns, making escape impossible. Astronaut Donald Pettit used the Tsiolkovsky Rocket Equation to figure out that limit. If earth were 50% more massive, he says, space travel with current rocket technology would be impossible. He didn’t figure what effects the greater mass would have on life, including human life, which would be correspondingly weighed down by excess gravity. If you feel sluggish now, think of carrying that extra weight! This would put a damper on the Olympics.
Good news, bad news: Two guys, Batista and Sloan, worked out at the University of Oxford. At The Conversation, they say, “We worked out what it would take to wipe out all life on a planet – and it’s good news for alien hunters.” The good news is that tardigrades (tiny but hardy animals) would probably survive extinction-level events, such as asteroid impacts, supernovae and gamma-ray bursts. The bad news is that humans and sentient beings probably would not. So unless one believes tardigrades are capable of radio astronomy, SETI should not be aiming telescopes at exoplanets that have been hit recently. There’s a lesson for habitability, too: planets subject to frequent bombardment by such terrors probably should not be considered habitable, even if all the other factors are present.
What is nature? A product of design or chance? Photo by David Coppedge
Do you get the impression that Earth might be so unique, so special, that it might be designed? (see 7/10/17). Why is that not a scientific conclusion? Must we force all observations into a materialistic, purposeless worldview? Our scientist of the month didn’t think so.